Medical Device Assembly

From a syringe… Ensure that a piston is used inside the syringe and that it is the correct type for the fluid being dispensed. For low viscosity fluids the double wiping white piston will prevent unwanted leakage out of the tip. For high viscosity or “stringy” fluids a red straight walled piston is recommended – the red piston also prevents “bouncing”. A double wiping blue piston is made available for the medium viscosity fluids. With some lower viscosity fluids there tends to be a small leakage after dispensing, even with a piston fitted. The TS250 and TS350 Series are equipped with a vacuum “suck back” adjustment to suspend the fluid at the end of the tip when the syringe assembly is not is use. From a valve… Each Techcon valve is fitted with a sealing design so that when the dispensing cycle is completed the fluid is suspended at the tip point until the next dispensing cycle. For needle and spray valves, a needle shuts off against a Delrin® seat. For the spool valves, a shaft retracts between 2 seals during opening and closing. Whilst in the closing phase a portion or fluid is sucked back into the dispensing tip to create a clean shut off, especially beneficial for stringy fluids. Diaphragm valves feature a moisture resistant barrier for moisture sensitive fluids such as medical grade cyanoacrylate. The diaphragm incorporates a domed end to shut off against the fluid body, creating a positive shut off. The TS5440 Microshot needle valve is designed with an extended needle shaft to shut off the fluid flow at the dispensing tip to prevent dripping, caused by back pressure in the “dead volume area”, in the hub of the dispensing tip. 8 – PRODUCING CONSISTENT SHOTS 7 – PREVENTING LEAKS AND DRIPS

Ensure fluid pressure and air pressure is not fluctuating. By using a high quality air regulator the source of air, supplying the dispensing equipment, is stable. All regulators should be fitted with a moisture trap to contain any moisture particles in the air source. Failure to use adequate filtration and moisture traps will result in contamination to the internal sensitive components of the dispensing controller. Environment temperature plays a large part in fluid dispensing. Some fluids will become thinner as the room temperature increases, throughout the day, resulting in faster and uncontrolled dispensing deposits. Maintaining and stable room temperature will ensure the fluid stays at the true viscosity during use. The final part, of the dispensing equipment, to touch the fluid, is the dispensing tip . Lower quality tips were found to have burrs and “flash” on the construction. Flash not only restricts flow rates but can break off into the dispensing fluid causing contamination. All Techcon Systems plastic consumable items are designed as a one use item. When the syringe is empty it should be discarded safely and new components should be used. Reusing plastic syringes increases the risk of contamination and inconsistency.

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Tel: +44 1908 686660 Fax: +44 1908 686836 info@adhesivedispensing.co.uk www.adhesivedispensing.co.uk